Method of setting protein containing coatings with ammonium



Patented Sept. 15, 1953 METHOD OF SETTING PROTEIN CONTAIN- ING COATINGS WITH AMMONIUM Jean E. Jones, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application April 29, 1952, Serial No. 285,087

16 Claims. 1

This invention relates to a technique of setting aqueous protein coatings characterized in that formaldehyde, acrolein or glyoxal is incorporated in the coating solution, and immediately after the solution has been coated onto a surface it is subjected to the action of gaseous ammonia. This invention relates to solutions of proteins in water per se and also to compositions in which the aqueous solution of protein carries therein a photosensitive salt, a pigment or a dye.

In the applying of protein coatings from aqueous solutions thereof, the coating at the time of application is in liquid condition, and in order to accomplish drying of that coating it is desirable that it first be set. This is ordinarily accomplished by immediately subjecting the liquid coating to a lowered temperature whereby the chilling of the coating causes gelling thereof. The coating may then be dried, such as by applying to the coating a current of dry air. In the chill-setting method, setting only occurs after the coating has been chilled to the setting temperature throughout. Where the chill-setting method is employed in paper coating, any delay of the setting will result in penetration of the paper by the coating liquid. Also, in the drying of the chilled layers it is necessary to guard against a somewhat elevated temperature in the drying air, as the application. of warmth may cause remelting. In the case of some types of proteins which may be employed in coating operations, chilling is ineffective to cause setting of the coating applied.

The setting of coatings of polyvinyl alcohol has been described in the prior art, but in those cases, particularly where gelatin has been mixed therewith, it has been necessary to incorporate both a heavy metal salt and boric acid therein to obtain a setting with ammonia.

One object of my invention is to provide a procedure for the fast setting of a liquid aqueous coating of protein. Another object of my invention is to make possible the drying of aqueous protein layers at high temperatures without remelting occurring, such as would be experienced where chill-setting is used. A further object of my invention is to provide a method of coating paper with aqueous solutions of proteins wherein the liquid coating composition sets rapidly and penetration of the paper sheet is reduced to a minimum. A still further object of my invention is to provide a method of setting liquid protein coatings in which the use of heavy metal salts in the coating liquid is avoided. A still further object of my invention is to provide a method for setting proteins in the form of their aqueous solutions by which method only clear coatings are obtained. A still further object of my invention is to provide a method of setting protein coatings in which lowering of the temperature is unnecessary. A still further object of my invention is to provide a method of setting photographic gelatin emulsion coatings at temperatures above the gelling point thereof. Other objects of my invention will appear herein.

I have found that aqueous solutions of proteins particularly gelatin, when applied to a surface of paper, film base, cloth or other surfaces may be substantially immediately set if formaldehyde (or acrolein or glyoxal) is incorporated in the coating composition and gaseous ammonia is applied to the liquid layer of aqueous protein. Such treatment changes the protein solution of the liquid-coated layer from the sol to the gel form. Under maximum conditions this setting up of the liquid coating occurs very rapidly (such. as on the order of 1 second or less). The time in which the setting up occurs depends on several factors as follows: i

1. Composition of the Ziquid.-It is desirable that the liquid coating composition contain at least 2% of gelatin or other protein to obtain setting or gelling in accordance with my invention. It the coating is applied on an absorptive surface or the like, even more dilute protein solutions may be set or thickened by my method. If 10% or more of gelatin or protein is present in the liquid composition, maximum speed of setting may be obtained. However, I have found that a concentration of 38% of protein in the coating composition gives the most useful range within which to operate.

2. Percent of formaldehyde in the composition-The percentage of formaldehyde used in the composition may be within the range of %,%-50% (based on the weight of the protein), although the most useful range has been found to be %-l0%. It may be stated as a general rule that, as the protein concentration in the coating composition increases, less formaldehyde is needed, whereas with coating compositions having a low protein concentration therein a higher percentage of formaldehyde is desirable. These proportions also are to be observed in the use of acrolein or glyoxal when those are employed instead of formaldehyde.

3. Concentration of NH3 in the fuming chamber.--Although I have found that a concentration of NH3 as low as .2% by volume in the gas of the fuming chamber is effective, I ordinarily prefer 3 to use therein a higher concentration of ammonia, such as .5% by volume or more. In general, as the concentration of the ammonia increases, the time of setting decreases.

4. Temperature of the surrounding gas-4n setting proteins in accordance with my invention, the surrounding gas may be at an elevated temperature, such as 150 F. or even more. However, my method may be carried out at any reasonable temperature within the range of 45.160 F. in operating my process it is, of course, necessary that the ammonia gas be kept from the coating composition prior to its spreading upon the surface on which it is coated, as otherwise setting up of the liquid composition while in the hopper or other container in which it is found would occur.

5. Method application of the ammon'ia.. The ammonia should be applied to the protein coating as soon as that coating has been applied to a surface, thereby avoiding ny movement in the liquid coating composition with reference to the surface to which it was applied. One very useful method of applying the ammonia is to direct the ammonia gas so that it impinges direct- 1y on the coated layer. Any of the various known methods of contacting gases with surfaces can be used. As higher concentrations of NH3 and rapid application of NH3 to the coated layer increases the speed of setting thereof, it is desirable to direct the ammonia gas to the layer to obtain setting in the shortest times.

I have found that my invention is useful for setting layers of gelatin or other protein which have been applied either clear or in dyed form to a supporting surface, such as layers of a thickness of DOGS-.025 inch. instead, the protein compositions may be in the form of photosensitive silver halide emulsions or in the form of pigment layers such as used for the baryta coating of photographic paper. I have found that my invention is particularly useful for the setting of photographic emulsions consisting of silver halide in a protein vehicle by coating out the composition as mentioned and then subjecting to fuming with ammonia gas, both at room temperature and at anytemperature which might be employed at this point. ihe photographic emulsion layer obtained is then dried without the necessity of using lowered temperatures.

My invention is applicable to emulsions generally in which the silver halid is in suspension in an aqueous solution of a protein at a pH such that'the protein will remain in solution at room temperature or slightly elevated. In the case of a photographic emulsion it may have commonly added materials, such as sensitizers, anti-foggants and the like, therein to aid the photograph ic properties. This may include both washed and unwashed photographic emulsions.

Another type of gelatin or other protein coating solution in which my invention is useful is that in which the gelatin is applied as a clear solution to form an overcoating on a support. If desired, a dye may be dissolved therein to impart artificial coloration to the protein layer. My in.- vention is also applicable to coatings in which the protein contains in suspension therein pigs ment particles, such as, for example, in the baryta coating of paper in which the protein is employed as the carrier for the pigment. Also, my invention is useful in the treatment of gelatinsilver halide emulsion layers where quick setting up and drying of the photosensitiv layer applied to a support is desirable.

If desired, the gelatin or other protein may be mixed with other polymeric materials with which they are compatible. It is desirable, however, that the protein constitute at least 20% of the polymeric material and at least 2 of the composition of the coating liquid. Some polymers which are useful for mixing with proteins, if that is desired, are resins, such as styrene-butyl acrylate-methacrylamide, disclosed in Fowler application Serial No. 272,709, filed February 20, 1952. Other polymers which may be employed are acrylonitrile-ethyl acrylate, known as Rhoplex resins, acrylonitrile-butadiene resins, styrene-butadiene resins, styrene-acrylonitrile resins, styrene-ethyl acrylate resins, styrene-butyl acrylate resins and polyvinyl acetate. In the use of such polymers the polymeric material in the coating composition should consist of 20-100% of gelatin or other protein and -0% of one of the polymers as listed above.

One of the types of coatings to which my invention relates is that of a gelatin-silver halide emulsion. My invention is applicable to photosensitive emulsions generally in which silver halide is in suspension in an aqueous solution of a protein Vehicle. The emulsion may also have other commonly added materials, such as sensitizers, matting agents, antifoggants, spreading agents and the like. These emulsions are prepared by first dispersing silver halide in a peptizing agent and forming th emulsion therefrom using gelatin or some other protein vehicle. Other protein vehicles which might be employed are soy protein, casein or blood albumin, particularly after these proteins have been subjected to trea ment with hydrogen peroxide at an alkaline pH as disclosed in application Serial No. 768,480 of Lowe and Gates. The emulsion is then coated out in the form of a thin layer onto a support therefor, such as paper or film base, which layer is then set and dried. In accordance with my invention formaldehyde or the like is incorporated in the emulsion composition and, at the time of coating, the emulsion layer is subjected to the action of gaseous ammonia. In the case of proteins, such as soy proteins, casein or blood albumin, the chill setting method, as referred to previously, is not even operable. In the case of photographic emulsions those having a concentration of gelatin or other protein of 3 %-7% exhibit good setting characteristics. With that concentration of gelatin a suitable proportion of formaldehyde is 1.7. to 2%, based on the weight of the gelatin in the emulsion. After the formalde hyde has been added'to the emulsion. it is desirable to coat out the same in a short time to. as sure the best working conditions.

Another type of use which can be of my invention is in the baryta coating of paper. By this method a small amount of formaldehyde, such as in the form of formalin, is added to the baryta coating composition (gelatin and BaSOr), and, immediately after applying to the paper, the paper is passed into a chamber containing ammonia therein sothat immediate setting cc ours. The coating may then be driedby a current of warm dry air. The advantage of this procedure is that a minimum of the coating composition penetrates into thepaper which is coated therewith.

Another type of: coating operation to which my invention is applicable is in the use of a clear coating of protein. For instance, an aqueous solution of gelatin, either with or without some polymer as mentioned herein, is mixed with a small proportion offormaldehyde andcoatedout Example 1 A fine-grained motion picture positive emulsion made by dispersing silver halide in gelatin and washed by chilling and noodling, which emulsion had a concentration of gelatin of 6%, was given a formaldehyde content of 2%, based on the weight of gelatin in the emulsion. The emulsion was coated out onto film base to a thickness of approximately .009 inch and the coating was subjected to fuming with ammonia. Substantially immediate setting occurred, and the emulsion layer was dried by applying thereto a current of dry air. Upon exposure and development the film showed satisfactory speed and contrast.

Example 2 A photographic emulsion was prepared by preparing a dispersion of silver halide in a solution of a phthalic anhydride derivative of gelatin. The dispersion formed was then converted to grains, which grains were washed and were then dispersed in an aqueous solution of gelatin so that the total percentage of gelatin in the photographic emulsion was 4%. The emulsion had a pH of 6.0. 4% of formaldehyde, based on the weight of the gelatin in the emulsion, was added thereto and the emulsion was coated out onto a cellulose acetate film support and set substantially immediately by passing through a fuming box supplied with ammonia gas. Almost immediate setting took place and the emulsion coating was dried by means of a current of warm dry air. A film was obtained showing good characteristics for normal photographic processing.

Example 3 300 cc. of washed grains of silver halide, pre pared by using oxidized casein as the peptizer, such as described in Lowe and Gates application Serial No. 768,480, were mixed with 300 g. of a 20% solution of hydrogen peroxide-oxidized casein at a pH of 6.5. Formaldehyde (1% based on the dry weight of casein) was added thereto and the emulsion was coated onto a film support, set by fuming with ammonia and dried by means of a current of warm dry air. After exposure and development the fumed films showed improved speed and contrast and a lower fog level than check coatings which were dried without fuming.

Example 4 68 cc. of grains of a silver halide dispersion, made by using the phthalic anhydride derivative of hydrolyzed gelatin as a peptizer, as described in U. S. Patent No. 2,614,928 of Yutzy and Frame dated October 21, 1952, were mixed with 70 g. of a 20% solution of casein which had been treated with hydrogen peroxide under alkaline conditions, the resulting emulsion having a pH of 6.5. The casein which was employed was one which had been oxidized by hydrogen peroxide at a pH of 10 for one hour at 35 C. There was then added to the emulsion 1.4 cc. of a 10% solution of formaldehyde. The emulsion was coated as a thin layer upon cellulose ester film base and was subjected to fuming with gaseous ammonia which resulted in setting the emulsion layer. The emulsion was then dried by subjecting to a current of warm dry air. After exposure and development the film exhibited the following characteristics: speed 5.40; contrast 1.92; fog .11..

Example 5 Washed silver halide grains were prepared as: described in the preceding example. A photosensitive emulsion was formed by mixing 68 cc. of those grains with 70 g. of a 25% solution of soybean protein which had been modified by treatment with alkaline hydrogen peroxide fora time. There was added then to the emulsion: 2 cc. of a 10% solution of formaldehyde. The:

resulting emulsion was coated onto cellulose ester film base and was set by passing through a fum ing box where it was treated with gaseous ammonia. The emulsion layer was then dried by treatment with warm dry air. A photographic film of good properties was obtained.

Example 6 A 7% solution of gelatin in water was prepared at F., and 0.7% of dry formaldehyde (based on the weight of gelatin), as formalin, and a spreading agent (saponin) were added thereto. This gelatin solution was coated onto abarytacoated paper base and the coating was set by fuming the same with air containing 1% of ammonia gas by volume. Setting of the coating was obtained in 6 seconds. Increasing the amount 01' formaldehyde used to 3% in such a procedure was found to decrease the setting time of the gelatin layer to 3 /2 seconds. The coating, after setting, was dried in a current of warm dry air. The temperature of the air containing ammonia, employed to set the coating, was 70 F.

Example 7 A solution was prepared of 16 parts of gelatin, 0.48 part of dry formaldehyde, a small amount of a wetting agent (saponin) and water to make a total of 400 parts, the temperature being at 105 F. to retain the gelatin in solution. The gelatin solution was coated onto an uncoated paper base and was set by fuming with ammonia as described in the preceding example. The coating was then dried by a current of warm dry air. There was then applied to this paper over the gelatin coating a coating of baryta containing 37.9% of solids of which at least 3.6% was gelatin and 2% of dry formaldehyde, based on the weight of the gelatin. This coating was set by ammonia fuming and dried. There was then applied to this sized and baryta-coated paper a photosensitive emulsion containing .05

mol of silver chloride, 15 grams of gelatin, 0.6. gram of formaldehyde and a spreading agent,

the whole being diluted with water to a total Weight of 345 grams. This emulsion layer was fumed with ammonia and dried by the use of a current of warm dry air.

Example 8 up in water to a total weight of 830 parts. This mixture was coated onto a baryta-coated paper base and the liquid coating thus applied was immediately set by fuming. with air containing ammonia. The coating. was then dried by means of a current of warm dry air.

Example 9 A mixture of 14 parts of gelatin, 42 parts of acrylonitrile-ethyl acrylate resin, known cornmercially as Rhoplex, 0.42 part of dry formaldehyde and a small amount of a spreading agent (a wetting agent) was made up with water to a total of 350 parts. This liquid composition was applied to a paper support and immediately set by fuming with ammonia. The coating was then dried by means of a current of warm dry an.

Example 10 A photographic emulsion was prepared containing .05 mol of silver chloride, grams of gelatin, 15 grams of Rhoplex, 0.6 part of formaldehyde, a small amount of a wetting agent and sufiicient water to make a total of 345 grams, and was coated onto a baryta-coated paper base. The liquid layer thus applied was immediately set by fuming with ammonia and was dried with a current of warm dry air.

Example 11 A mixture was prepared of 16.8 parts of casein (which had been oxidized by treating with hydrogen peroxide under alkaline conditions), 16.8 parts of styrene-butyl acrylate-methacrylamide resin, 0.84 part of dry formaldehyde, spreading agent (saponin) and sufiicient water to make a total of 223 parts. This liquid composition was coated onto a baryta-coated paper and the liquid coating thus obtained was immediately set by fuming with ammonia and was dried with a current of warm dry air.

Example 12 A mixture was prepared containing 226 parts of casein which had been oxidized with H202 under alkaline conditions, 22.6 parts of acrylo- .nitrile-ethyl acrylate resin known as Rhoplex, 1.12 parts of dry formaldehyde, a small amount of spreading agent and sufficient water to make a total of 400 parts. The liquid composition thus obtained was applied as a layer onto a baryta-coated paper support, which coating was immediately set after application by fuming with ammonia. The coating was then dried in a current of hot dry air.

Example 13 A mixture was prepared containing 226 parts of casein which had been oxidized with H202 under alkaline conditions, 1.12 parts of dry formaldehyde and saponin together with. sufiicient water to make a total of 300 parts. The liquid composition thus obtained was applied to a baryta-coated paper and was set by fuming with ammonia and drying in a current of warm dry air.

Example 14 A 4% solution of gelatin was prepared by dissolving the gelatin in water at 105 F. There was then added 2% of formaldehyde (based on the weight of gelatin) and a small amount of spreading agent (saponin). The liquid composition was applied as a coating onto a raw paper stock whereupon the coating set by fuming with ammonia and drying in a current of warm dry air.

. Setting Percent NHa by volume in the air time, Sm

The ammonia-set paper stock was fully as good as that which had been processed by a chillsetting procedure.

Example 16 A mixture of 30 parts of casein, which had been oxidized with H202 under alkaline conditions, 525 parts of blanc fiXe (55% solids), 1.48 parts dry formaldehyde and spreading agent to make the total 685 parts was prepared and coated onto a paper base of raw stock. The coating was then set by fuming with ammonia and drying with warm dry air.

Earample 17 A solution was prepared of 14 parts of gelatin, 1.35 parts of tartrazine, 0.42 part of dry formaldehyde, spreading agent and sufiicient water to make a total of 350 parts, and this solution was coated onto a film base. The coating thus obtained set rapidly by fuming with ammonia and was then dried by means of a current of warm dry air.

Erample 18 A solution was prepared of 14 parts of gelatin, 0.81 part of crystal violet, 0.42 part of formaldehyde, spreading agent and sufficient water to make a total of 350 parts. The thus-prepared solution was coated onto a film base, quickly set by fuming with ammonia and drying in a current of warm dry air. There was thus applied a backing layer to the film base.

Example 19 A coating of photographic emulsion containing formaldehyde was coated on baryta-coated paper, set by fuming with ammonia and dried with a current of warm dry air. A second coating of the emulsion was then applied over the first, ammonia fuming was applied rapidly setting the second emulsion coating and warm dry air was applied, which dried the second layer. Thus was obtained a photographic product having 2 emulsion coatings.

Example 20 A silver chloride emulsion containing 4.7% of formaldehyde, based on the weight of gelatin, was coated onto a paper support and the coating was fumed with air containing 0.7% NH3 by volume. The first coat was Well set and 36 seconds later a second emulsion coat containing 3.5% of formaldehyde, based on the weight of the gelatin, was applied over the first emulsion coating Ammonia fuming was applied which quickly set the second coating, and the whole was then dried by means of a current of warm dry air.

Example 21 An emulsion was prepared of 0.1 mol of silver chloride, 41.5 grams of gelatin, grams of styrene-butyl acrylate-methacrylamide resin, 2.2 grams of formaldehyde and suflicient water to make the total mass 635 grams. The emulsion so prepared was applied to baryta-coated paper and the liquid coating was fumed with ammonia and dried with a current of warm dry air.

Example 22 A photosensitive gelatin emulsion, containing formaldehyde, was applied to a paper support set with amomnia and was then overcoated with a solution of gelatin containing no formaldehyde. The coating was then fumed with ammonia and it was found that the overlayer set rapidly, the formaldehyde in the first coat contributing to the setting thereof. The emulsion which was employed consisted of .1 mol of silver chlorobromidc, 43 grams of gelatin, 0.8 gram of formaldehyde and sufficient Water to make a total weight of 575 grams. This emulsion was coated on a baryta-coated paper and was immediately overcoated with 2.5% gelatin solution.

Example 23 A 4% solution of gelatin was prepared and 7.5% (based on the weight of the dry gelatin) of glyoxal was incorporated therein. The dissolving of gelatin in water is conveniently carried Example 24 345 grams of a photosensitive silver chloride emulsion containing grams of gelatin, 7.2 grams of silver chloride and 1.1 grams of glyoxal was coated onto a baryta-coated paper base at the rate of 905 square feet per mol of silver chloride, The liquid coating was fumed with ammonia whereby setting of the emulsion layer took place in a time less than seconds. The coating thus applied was dried in a current of dry air. The photographic paper thus obtained was exposed and processed and was found to be satisfactory for photographic purposes.

In the setting of protein coating compositions in accordance with my invention, ammonia is ordinarily employed due to its effectiveness and availability. Nevertheless, it is to be noted that other volatile amines, such as monomethyl amine, are operative in this connection and may be employed if desired. 1 1

One feature of my invention is that the protein coating composition, after setting, can be dried by means of air at an elevated temperature, which may not be true in the case of chill setting. For instance, when a silver halide emulsion containing gelatin and formaldehyde is coated onto a baryta paper stock, chill setting of this coating might be accompanied by an air temperature of 45 F. dry bulb and. 39 wet bulb.

Then, for the drying of the coating, the temperature is limited, such as within the range of 65-90 F. dry bulb. However, the same emulsion, in setting by ammonia fuming, can be set, for instance, with an NI-Ia containing gas having a dry bulb temperature of 87 F. and a wet bulb temperature of 62 F. After this setting has occurred, the drying operation can be carried out by means of air heated to a temperature of F. If air of this temperature were employed for drying the chill set emulsion layer, remelting thereof would ordinarily occur.

The application of coatings, in accordance with my invention, may be to any of the usual types of surfaces to which coatings are applied, such as paper, cellulose ester sheeting, glass, cloth, metal foil and the like. These coatings may be applied by any conventional method of applying coatings to such surfaces, such as, for instance, by dip coating or hopper coating.

This application is a continuation-in-part of my copending application Serial No. 69,821, entitled Method of Setting Photographic Emulsions, filed January 7, 1949, now abandoned.

I claim:

1. In the application of coatings from solutions in water of at least 2% concentration of proteins having a pH at which the proteins will remain in solution at room temperature to a surface to be coated therewith, the method of quick setting those coatings which comprises incorporating in the protein solutions 4-50% (based on the weight of the protein) of an aldehyde selected from the group consisting of formaldehyde, glyoxal and 'acrolein, coating out the solution in fluid form onto the surface and fuming the resulting coating with gaseous ammonia whereby rapid setting of the coating is obtained without chilling of said coating being necessary.

2. In the application of coatings of solutions in water of at least 2% concentration of protein having a pH at which the protein will remain in solution at room temperature to a surface to be coated therewith, the method of quick setting those coatings which comprises incorporating in the coating composition l -60% (based on the Weight of the protein) of formaldehyde, coating out the solution in fluid form onto the surface and fuming the resulting coating with gaseous ammonia whereby rapid setting thereof is obtained without chilling of said coating being necessary.

3. In the application of coatings of solutions in water of at least 2% concentration of protein having a pH at which the protein will remain in solution at room temperature to a surface to be coated therewith, the method of quick setting those coatings which comprises incorporating in the coating composition 4-50% (based on the weight of the protein) of glyoxal, coating outthe solution in fluid form onto the surface and fuming the resulting coating with gaseous ammonia whereby rapid setting thereof is obtained without chilling of said coating being necessary.

4. In the application of coatings of solutions in water of at least 2% concentration of protein having a pH at which the protein will remain in solution at room temperature which protein solutions contain therein in suspension silver halide particles, to a support therefor, the method of quick setting those coatings which comprises incorporating in the protein solution containing the silver halide in suspension therein //,-50% (based on the weight of the protein) of an alde hyde selected from the group consisting of formaldehyde, glyoxal and acrolein, coating out the protein composition in fluid form onto the support and fuming the coating with gaseous ammonia whereby rapid setting of the coating is obtained without chilling thereof being necessary.

5. In the application of coatings of solutions in water of at least 2% concentration of gelatin having silver halide particles suspended therein and a pH at which the gelatin will remain in solution at room temperature, to a support therefor, the method of quick setting those coatings which comprises incorporating in the gelatin solution containing silver halide suspended therein /;-50% (based on the weight of the protein) of an aldehyde selected from the group consisting of formaldehyde, glyoxal and acrolein, coating out the gelatin solution in fluid form onto the support and fuming the resulting coating with gaseous ammonia whereby rapid setting of that coating is obtained without chilling thereof being necessary.

6. In the application of coatings from solutions in water of at least 2% concentration of gelatin having a pH at which the gelatin will remain in solution at room temperature, to a surface to be coated therewith, the method of quick setting those coatings which comprises in corporating in the gelatin solution 1-50% (based on the weight of the gelatin) of an aldehyde selected from the group consisting of formaldehyde, glyoxal and acrolein, coating out the gelatin solution in fluid form onto the surface and fuming the coating with gaseous ammonia whereby rapid setting .of that coating is obtained with-- out chilling of the same being necessary.

'7. In the application of coatings from solutions in water of at least 2% concentration of gelatin having a pH at which the gelatin will remain in solution at room temperature to a surface to be coated therewith, the method of quick setting those coatings whichcomprises incorporating in the gelatin solution 4-50% (based on the weight of the gelatin) of formaldehyda'coating out the gelatin solution in fluid form onto the, surface and fuming the coating with gaseous ammonia whereby rapid setting thereof is obtained without chilling of said coating being necessary. 8. In the application of coatings from solu'= tions in water of protein of 3-8% concentration having a pH at which the protein will remain in solution at room temperature, to a surface to be coated therewith, the method of quick setting those coatings which comprises incorporating in the protein solution /2-10% (based on the weight of the protein) of formaldehyde, coating out the protein solution in fluid form onto the surface and fuming the coating with gaseous ammonia whereby rapid setting thereof is obtained without chilling of said coating being necessary.

9. In the application of coatings from solutions in water of 3,-8% concentration of gelatin having a pI-I at which the gelatin will remain in solution at room temperature to paper, the method of quick setting those coatings which comprises incorporating in the gelatin solution -10% (based-on the weight of the gelatin) of formaldehyde, coating out the gelatin solution in fluid form onto the paper and fuming the coating with gaseous ammonia whereby rapid setting thereof is obtained without chilling of the same being necessary.

10. In the application of coatings from solutions in water of gelatin of at least 2% concentration having silver halide particles suspended therein and a pH at which the gelatin will remain in solution at room temperature, to a paper support therefor the method of quick set-- ting those coatings which comprises incorporating in the gelatin solution -10% (based on the weight of the gelatin) of formaldehyde, coating out the gelatin solution in fluid form onto the paper support and fuming the same with gaseous ammonia whereby rapid setting of the gelatinsilver halide coating is obtained.

11. In the application of coatings, from solutions in water of at least 2% concentration of gelatin having dispersed therein particles of barium sulfate and a pH at which the gelatin will remain in solution at room temperature, to paper, the method of quick setting those coatings which comprises incorporating in the gelatin-barium sulfate composition /210% (based on the weight of the gelatin) of formaldehyde, coating out the" gelatin composition in fluid form onto the paper and fuming the paper with gaseous ammonia whereby rapid setting thereof is obtained with-- out chilling of said coating being necessary.

12. A method of preparing photographic paper which comprises coating a paper support with an aqueous solution of at least 2% concentration of gelatin having barium sulfate particles suspended therein, a pH at which the gelatin will remain in solution at room temperature and 10% of formaldehyde (based on the weight of the gelatin), setting the coating by fuming with ammonia and drying, followed by applying to the coated paper a coating of an aqueous solution of gelatin of at least 2% concentration having silver halide suspended therein, a pH at'which the gelatin will remain in solution at room temperature and /2-10% of formaldehyde (based on the Weight of the gelatin) fuming the resulting coating with gaseous ammonia whereby rapid setting of the coating is obtained and then drying this layer by means of a current of warm dry air.

'13. In the application of coatings of solutions in water of at least 2% concentration of casein having a pH at whichthe casein will remain in solution at room temperature to a surface to be coated therewith, the method of quick setting those coatings which comprises incorporating in the casein solution A;.-5O% (based on the weight of the casein) of formaldehyde, coating out the casein solution in fluid form onto the surface and fuming the coating with gaseous ammonia whereby rapid setting of the coating is obtained.

14. In the application of coatings from solutions in water of at least 2% concentration of casein having silver halide in suspension therein and a pI-I at which the casein will remain in solution at room temperature to a support therefor, a method of quick setting those coatings which comprises incorporating in. the casein solution -50% (based on the weight of the casein) of formaldehyde, coating out'the solution in fluid form onto the support and fuming the coating with gaseous ammonia whereby rapid setting thereof is obtained.

15. In the application of coatings from solutions in water of at least 2% concentration of protein having barium sulfate particles suspended therein and a pH at which the protein will remain in solution at room temperature to paper which comprises incorporating in the protein-barium sulfate composition /;,50% (based on the weight of the protein) of an aldehydeselected from the group consisting of formaldehyde, glyoxal and acrolein, coating out the protein composition in fluid form onto the paper and fuming the coating with gaseous ammonia whereby rapid setting thereof is obtained Without chilling of said coating being necessary.

16. In the application of coatings of gelatinsilver halide to paper from solutions in water of 38% concentration of gelatin having silver halide particles suspended therein and a pH at which the gelatin will remain in solution at room temperature to a paper support, the method of quick setting those coatings which comprises incorporating in the gelatin-silver halide composition -10% of formaldehyde (based on the weight of the gelatin) coating out the gelatinsilver halide composition in fluid form onto the paper support and fuming the coating with gaseous ammonia whereby rapid setting of the emulsion coating is obtained.

JEAN E. JONES.

No references cited. 

4. IN THE APPLICATION OF COATING OF SOLUTIONS IN WATER OF AT LEAST 2% CONCENTRATION OF PROTEIN HAVING A PH AT WHICH THE PROTEIN WILL REMAIN IN SOLUTION AT ROOM TEMPERATURE WHICH PROTEIN SOLUTIONS CONTAIN THEREIN IN SUSPENSION SILVER HALIDE PARTICLES, TO A SUPPORT THEREFOR, THE METHOD OF QUICK SETTING THOSE COATINGS WHICH COMPRISES INCORPORATING IN THE PROTEIN SOLUTION CONTAINING THE SILVER HALIDE IN SUSPENSION THEREIN 1/4-50% (BASED ON THE WEIGHT OF THE PROTEIN) OF AN ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE, GLYOXAL AND ACROLEIN, COATING OUT THE PROTEIN COMPOSITION IN FLUID FORM ONTO THE SUPPORT AND FUMING THE COATING WITH GASEOUS AMMONIA WHEREBY RAPID SETTING OF THE COATING IS OBTAINED WITHOUT CHILLING THEREOF BEING NECESSARY. 